Air pressure stacking apparatus for metal sheets



Jan. 27, 1970 w. WALDURA 3,491,902

I AIR PRESSURE STACKING APPARATUS FOR METAL SHEETS Filed Oct. 16, 1967 I-IIL United States Patent T 3,491,902 AIR PRESSURE STACKING APPARATUS FOR METAL SHEETS Walter Waldura, St. Ingbert, Saar, Germany, assignor to Moeller & Neumann GmbI-l (Verwaltungsgesellschaft, Ollene Handelsgesellschaft), Ingbert (Saar), Germany Filed Oct. 16, 1967, Ser. No. 675,554 Claims priority, application Germany, Oct. 22, 1966,

Int. Cl. B65g 57/ 04; B66c 17/04 US. Cl. 2146 3 Claims ABSTRACT OF THE DISCLOSURE A stacking apparatus for surface sensitive metal sheets which are supported by mechanical means upon entering the stacking box and released subsequently to drop on a stacking table and comprising the combination of a sheet to be stacked, particularly the first sheet of a stack, and a compressed air supply source for producing a contained air flow to aid in partially supporting the first sheet of a stack and to fully support the subsequent sheets for lowering on the stack.

The invention relates to an air pressure stacking apparatus for metal sheets in which the stacking box has smooth laterally adjustable side Walls and a vertically movable stacking table with surface interruptions for receiving and discharging a stack of metal sheets. The surface interruptions are necessary to allow the introduction of a chain conveyor or in the case of naturally movable stacking tables the arms of a gripping crane for removing the sheet stacks.

It is known that in an air-pressure stacking apparatus the incoming sheets are suspended or held aloft by the effect of an air flow until they leave a driving roller pair located at the inlet end of the stacking box and that the sheets are subsequently lowered gently on the support table or on the previously deposited metal sheet. This is also the case for the first sheet of a quantity of thin metal sheets to be stacked and for which air pressure stacking apparatus have been built exclusively to date. Metal sheets of medium thickness above approximately 3 mm. have hitherto not been stacked by means of air pressure because the air flow has not been sufficient to provide the necessary support in keeping the sheets suspended or for lowering such sheets in a gentle manner.

The stacking of metal sheets by means of air pressure is more complicated and is usually employed only when the sheets have a sensitive surface. There is also an urgent need to have air pressure stacking apparatus which would be capable of stacking also medium sized sheets above 3 mm. thickness in a careful manner when the sheets are surface sensitive.

The air stacking apparatus according to this invention fulfills this need by using known mechanical means which are operable independently of the air flow to provide additional, temporary support of the first incoming sheet of a stack and particularly for air pressure stacking of sheets above 3 mm. thickness.

The invention is based on the recognition that it was not the weight of the sheets which constituted the impediment of using air pressure stacking also in the area of medium size sheets but the fact that the interruptions in the platform surface of the stacking table which are necessary, produce such a great loss of air and air vor-texes that the air flow is just suflicient to support thin sheets and is not able to support sheets of more than 3 mm. thickness. By the new process of stacking the first sheet Patented Jan. 27, 1970 according to the invention mechanically the exclusive air pressure stacking is made possible for all subsequent sheets because the first sheet covers the interruptions in the table top of the stacking table and renders them ineffective.

It is furthermore surprising that even the first mechanically stacked sheet does usually suffer no damage by travelling on the known support means carrying rollers and being ajustable from an ineffective position to a position extending from the side walls of the stacking box and on which the first sheet travels with its edges, because the continuously effective air flow still fulfills at least part of its purpose and the mechanical support means have to support only a part of the sheet weight. Furthermore it would not be particularly inconvenient to subject the first or lowermost sheet of a sheet stack to a special control for surface faults. The fact that all other subsequent sheets of medium size thickness may be air pressure stacked absolutely without support contact is a considerable advance in the art.

As a further step in accomplishing the object of the invention an advantageous improvement and augmentation of the air flow has been contemplated. In order to admit the air flow as closely as possible under the inlet plane of the sheets into the stacking box the invention provides that the lower driving roller of the driving roller pair disposed at the inlet of the stacking box is constituted as a grooved roller whereby the nozzles of the air supply may enter into the grooves of this lower driving roller.

In the attached drawing an embodiment of the air pressure stacking apparatus according to the invention has been illustrated. In this drawing:

FIGURE 1 shows a cross-section through the stacking box of the invention; and,

FIGURE 2 is a partial longitudinal section of the inlet region of the stacking box of FIGURE 1,

The stacking box proper is constituted in a known manner of two lateral beams 1, 2 having smooth side walls 1a, 2a which are spaced from each other at the particular distance required for receiving incoming sheets 3 and the walls are laterally adjustable to accommodate varying widths of sheets. The side walls 1a, 2a have at the inlet level of the sheets a row of circular openings through which support rolls 4, 5 may be advanced in a known manner when a sheet 3 is introduced. The support rolls 4, 5 may be quickly retracted by means of hydraulic drives 4a, 5a in order to release a sheet which has been introduced and allow it to sink on the stacking table 6. Instead of the support rolls 4, 5 other known mechanical means may be provided to support an incoming sheet 3, for example turnstile wheels or the like.

The stacking table 6 is constituted of a number of spaced column 6a whose cross-beam 6c is covered at the top with wooden boards 6b forming an interrupted platform. The columns 6a rest on intermediate plates 7 and cross-supports 8 which are guided laterally in a known manner over end rolls 8a and are vertically adjustable. The stacking table 6 with the platform of wooden boards 6b forms thus a stacking floor which may be lowered, and the interruptions of the floor are necessary because the stacking table floor must be lowered below the plane of the conveyor chains 9 which remove a stack of sheets laterally from the stacking apparatus. But also in the case of laterally discharging stacking carriages these interruptions of the stacking floor would be necessary in order to reach with the gripper arms of a crane under the stack sheets.

The stacking apparatus described above is basically known. Each individual incoming sheet 3 is supported by the support rolls 4, 5 until it has left the inlet driving roller pair 10, 11 and comes to rest at an abutment not shown. When the support rollers 4, 5 are retracted each sheet drops down on the stacking table 6 which is lowered stepwise as the stack grows until a completed stack is taken over and removed by the conveyor chains.

The novel feature of the invention is to combine the mechanically operated supporting means with an air supply at the inlet end so that also sheets of over 3 mm. thickness and greater length may be stacked by means of the air flow without any surface contact, as it is already known for thin sheets below a 3 mm. thickness. The air supplied by a blower (not shown) enters an air conduit 12 from which individual nozzles 13 project and these nozzles extend into the grooves of the lower driving roller 11 constituted as a groove roller. In this manner it is obtained that the strong air flow is admitted directly under the incoming sheets. According to the invention the stacking apparatus illustrated is so operated that in each instance the first sheet of a new stack, i.e. if the stacking box is empty, is guided over the extended support rolls 4, 5 and this sheet, after having been lowered onto the stacking table 6 forms a closed floor for the stacking apparatus. In view of the fact that now the side walls 1a, 2a as well as the lowered first sheet 3 from a substantially closed space or trough one can produce such a strong laminar air flow under the subsequent incoming sheets that they may be stacked without the additional support of the support rolls 4, 5 and carried by the air flow. In this respect it is essential that during the mechanical stacking of the first sheet by means of the support rolls 4, 5 the stacking table 6 is at a sufiiciently high level that the first lowered sheet is still inside of the lower level of the side walls 1a, 2a and this relationship must be maintained for all subsequent sheets in order to make sure that in each instance the uppermost sheet of the stack forms with the side walls 1a, 2a a substantially closed trough in order to avoid as much as possible any loss of air flow.

What is claimed is:

1. Stacking apparatus for metal sheets comprising, in combination, a stacking box having a pair of side walls arranged in spaced parallel relationship for accommodating metal sheets to be stacked therebetween, said side walls having an inlet for said metal sheets at one end, a vertically adjustable stacking table having a horizontally extending, interrupted floor arranged to be accommodated between said side walls for supporting said metal sheets in a stacked relationship, means for sequentially introducing metal sheets in a substantially horizontal plane into said stacking box through said inlet end between said side walls for subsequently forming a vertical stack of said sheets on said stacking table, retractable means in said side walls movable into an extended position within said stacking box for supporting the first metal sheet introduced into said stacking box, said retractable means being movable into a retracted position to permit said first metal sheet to drop onto said stacking table and close the interruptions in said stacking floor, means for introducing pressurized air into said stacking box through said inlet end in a plane closely adjacent the inlet plane of said metal sheets to form an air cushion for said metal sheets introduced into said stacking box, said first stacked sheet as well as the uppermost sheet in said stack being positioned above the bottom edges of said side walls to form with said side walls a substantially closed trough for minimizing the loss of pressurized air introduced in said stacking box to additionally support said first metal sheet on said extended support means and for fully supporting the subsequent metal sheets introduced into said stacking box with said retractable support means in the retracted position at all times after the first sheet has been deposited for sequential dropping of said subsequent metal sheets in a stacked relationship on said stacking table.

2. Stacking apparatus in accordance with claim 1 wherein said metal sheet introducing means include a pair of driving rolls arranged in vertically stacked relationship adjacent said side walls inlet end, the lower of said driving rolls being provided with a plurality of axially spaced annular grooves and wherein said pressurized air is introduced into said stacking box through said lower driving roll annular grooves.

3. A method of stacking metal sheets in a stacking box having a pair of side walls arranged in spaced parallel relationship and a vertically adjustable stacking table having a horizontally extending, interrupted floor arranged to be accommodated between said side walls for supporting said metal sheets in a stacked relationship comprising the steps of, positioning sheet support means within said stacking box between said side walls, introducing a first metal sheet in a substantially horizontal plane into said stacking box between said side walls in supported relationship with said support means, withdrawing said first sheet support means to permit said first metal sheet to drop onto said interrupted floor 'to close the interruptions in said stacking fioor, sequentially introducing subsequent metal sheets into said stacking box between said side walls in a substantially horizontal plane while maintaining said sheet support means in a withdrawn position, introducing pressurized air into said stacking box closely adjacent the inlet plane of said metal sheet for forming an air cushion under said metal sheets to permit said metal sheets to drop gently without utilizing the support means onto the previously stacked metal sheets on said stacking table, vertically adjusting said stacking table to maintain said first stacked sheet as well as the uppermost sheet in said stack above the bottom edges of said side walls to form with said side walls a substantially closed trough for minimizing the loss of air introduced into said stacking box.

References Cited UNITED STATES PATENTS 2,261,972 11/1941 Matthews 27174 2,637,450 5/1953 Eshelman 214-6 X 2,645,480 7/1953 Long 271-86 X 2,985,322 5/1961 Parker 2146 9 3,224,761 12/ 1965 MeyerJagenberg 271-68 3,321,202 5/1967 Martin 27l76 X 3,381,829 5/1968 Turner 214-6 FOREIGN PATENTS 812,537 9/1951 Germany.

GERALD M. FORLENZA, Primary Examiner ROBERT J. SPAR, Assistant Examiner US. Cl. X.R. 

